Process for producing beta-aminonitriles and beta-aminoesters



PROCESS FOR rnonucn'vo fi-AWONITRIIES ANn -AlvrNonsrnns William H. Selcer, TexasCity, Tern, .assignor to Monsanto ChemicalCompany, St. Louis, Mo., a corporation of Delaware No Drawing. Fiied Ang. 2s, 1957, Ser. No. ssaozs 7 Claims. c1. ass-465.5

mary amines react readily with esters of afi-unsaturated carboxylic acids such as methyl acrylate, for example, to yield fi-aminopro'pionates. Generally, amines react with mo-unsaturated acid derivatives of the acrylate type such as the lower aliphaticesters and nitriles of acrylic acid, methacrylic acid and crotonic acid without the aid of a catalyst. However, in this addition reaction steric effects are very imp'ortantand the size and branching of the alkyl groups have a definite influence on the reaction.

Yields, for example, reported for theireaction of acrylonitrile with tert-butylamine have been considerably lower than for the other butylarnines. This decrease in yield is even more pronounced with tert-octylamine v where the use of elevated temperatures, extended reaction time, or basic catalysts have all failed to give yields above 30%. The use of an acidic catalyst to overcome this dii ficulty has been described but certain losses of the aminefre- 'actant must be tolerated if it is to be used. Theoretically,

the amine can be recovered by reaction of the acid derivative with a stronger base.

as an additional reactant, acid losses o'cicurin therecove ry step, and the distillation system for recovery of the product is complicated by the 'presenceof salts.

1 Recently, it has-been discovered that these difiiculties in the prior art can be obviated to 'a great extent by employing 'water as a catalyst in'the addition reaction between amines which are characterized by steric hindrance and the a,fiunsaturated acid derivatives to give fi-aminonitriles and fi-aminoesters. The use offwate'r as V I Practically, however, this represents an additional step in the process as well tetramer and hydrogen cyanide, respectively.

4 2,982,782 ...PQ-Q!!Ped May 2, 1961 2 these higher amines can be materially increased by employing-a water-soluble cyanoethylatedamine as asolubilizer ,for the water catalyst in the reaction of these amines with, cap-unsaturated acid derivatives.

According tothe invention, fi-aminonitriles and 13- aminoesters are produced by reacting tert-carbinamines of the formula wherein .R, .R' and .R" .are chosen from the group consisting of alkyl, cycloalkyl, aryl, alkaryl and aralkyl radicals containingfrom 1 to 12 carbon atoms witha compound chosen from the group consisting of the lower aliphatic esters and .nitriles of tt-unsaturated acids in the presence ofa catalytic amount of water and asolubilizer therefor chosen from the group consisting of watersoluble cyanoethylated amines which are not subject to further reactionwith the a,/3-unsaturated acid derivatives under mildly alkaline conditions.

The following examples are presented to illustrate the inventionbut are not to be construed as limiting it in any manner. u

- EXAMPLEI A vseriesrof..experi n 1er 1ts were made in which tertnonylami-n'e and', tert-do'decylamine were reacted with acrylonitrile.

The :nonylami-ne land vdodecylamine employed were mixtures pf isomers of essentially tert-fcar- ,binamine structure, obtained, by the Ritter reaction of propylene .trimer and hydrogen c'yanide,,and propylene In one experiment, precautions were taken to use substantially anhyd us re ge t .1 th seco d. w r wa dde as a catalyst and in the third a solubilizer was added yvith water catalyst. The reactions were carried out in a 3001111., round-bottom, three neck flask fitted with 2. 250-1111. dropping funnel, a thermometer, a stirrer, areflux condens'er and aheatingmantle. The amine to be reacted, or the .amine andwater, or .the amine, water d .s ilize were s s d t h fla k s r nd heated to the temperature ofhthe ,l'owest' boiling reactant. The acrylonitri le was then added drop-wise from the funnel over a period of app'roximatelyllS "to minutes.

, After addition of' theinitrile wascompleted, the reaction mixture was refluxed for a period of one hour. Thereafter it was cooled, transferred to a flask fitted with a 6-in. -x l-in: distillation column paelgedwithglass beads and having ahead which wascooled by circulating jice a catalyst provides excellentyields' on a comparative basis." However, on anabsolute'basiswith amineshaving' a higher number of carbon atoms, such as nonylamine and higher, the yields still'leave something to be fdesired; It has now been determined that yields from b i was f al l-ated 1 7 tog th r w hfla obtained in t e variou ir ns are .P I

water, 'and' distilled. "The ,water and acrylonitrile were removed at atmospheric pressure while the excess amine Iandproduct aminonitrile wereyseparated by vacuum dis- 'tillation'-'(-0'1-5-'min.- of Hg absolute). Conversion of ylon r to th ire neetive prod fi-(ter n zny iino) propionitrile," 1d fi (tert-dodecylamino)propionitrile each ,case. Spec ific reaction conditions sented in Table I V Tor cent 2 i ,Added to the reaction flask and heated to about 79 C.

required to "solubili'ze the EXAMPLE n The same apparatus employed in Example I was used in this experiment. About 46.2 g. (0.25 mole) of tertdodecylamine, 36.0 g.- of fl-(ethylamino)propionitrile, 4.6

g. of H and 0.25 g. of copper powder were charged 5 (The copper powder was added to inhibit polymerization of the ethyl acrylate.) While this mixture was stirred continuously, 25.0 g. (0.25 mole) of ethyl acrylate was removalof unreactedtert-dodecylamine, ethyl acrylate and the 18-(ethylamino)propionitrile solubilizer and recovery. of the product, ethyl-fl-(tert-dodecylamino)propionate. The yield of product was 44.3 g. representing a conversion of 62.3% based on the, tert-dodecylamine charged.

When this experiment was repeated with all conditions and procedures identical except that the B-(ethylamino)- propionitrile was not employed as solubilizer, the conversion of tert-dodecylamiue to. ethyl-,B-(tert-dodecylamino)propionate was only 38.8%.

EXAMPLE III The suitability of various water-soluble cyanoethylated aminesas solubilizers for the water catalyst in the reaction of t-c-arbinami-nes with a,B-unsaturated acid derivatives was, determined by a series of simple tests. 'Into 'each of a number of test tubes there was placed drops of the t-nonylamine used in Example I, 13 drops of acrylonitrile, and- 3 drops of water. The amount of amine and nitrile represented a 1:1 ratio on a mole weight 35 basis and the amount of water was equivalent to 10% by weight of thegamine reactant. The test tubes were placed in an oil bath 'and heated until the contents were at a temperature of approximately 75 C. To these tubes there was then slowly added dropwise fl-(n-butylamino)- 40 propionitn'le, 8-(cyclohexylamino)propionitrile, fl-(ethylamino)propionitrile, 3,5 iminodipropionitrile, {I (nbutylarnino)dipropionitril=e and B (t-octylamino)propionitrile, respectively, until all the water present went into solution in the amine. Solution was effected with each one ofthese solubilizers in the amounts indicated below. The solubilizers are arranged in the order of preference for their use.

v Drops required B,fl-Iminodipropionitrile -1 7 [3-(Ethylamino)propionitrile 8 [3-(Cyclohexylamino)propionitrile 15 B-(n-Butylamino)dipropionitrile l6 fir(n-Butylamino)propionitrile '26 These same tests were repeated using-46 dropsof the t-dodecylamine,.13 drops of acrylonitrile" and 4 drops of water. Amou'nts'of the cyanoethylated airlines in 'drops "water. inthis case g were as'followsz, h

Drops required fl-(t-Butylamino)propionitrile- 15 fl-(Ethylamino)propionitrile 3-.(n Butylamino)dipropionitrile -4---." 60 .55

amines required to solubilizethe wate'r were as. follows:

' Drops required ,B (Ethylaniino)propionitrilelg a The data from the examples show clearly that the addi tion of water-soluble cyanoethylated amines etfects solubilization of water in the higher t-carbinamines which are characterized by steric hindrance in a system containing these amines, acrylonitrile or ethyl acrylate, and water. By so doing they facilitate the functioning of the water as a catalyst and result in significant increases in yields in the addition reaction of these so-called hindered amines and a,fi-unsaturated acid derivatives. It is understood, of course, that such cyanoethylated amine solubilizers to be efiective must not, be subject to further reaction with the cap-unsaturated acid derivatives under the conditions of the addition reaction, i.e., under mildly alkaline conditions.

Some'variations may be made in reaction conditions from those given in the example without departing from the scope of the invention. Other suitable amines in addition to those mentioned in the examples which may be reacted according to the process of the invention include, for example, 3-methyl-3-aminohexane, 3-ethyl-3-amino pentane, tert-pentadecylamine, 2-cyelohexyl-2-aminobutane, 2-cyclopentyl-2-aminopropane, 2-phenyl-2-aminopropane, 2-benzyl-2-aminohexane, 2-tolyl-2-aminobutane, l,l-di-(p-rnethylphenyl)-1-arninoethane, l cyclohexyl-lbenzyl-l-aminopropane, and the like. Likewise, in addition-to those given in the examples, suitable nitriles and lower aliphatic esters of tsp-unsaturated acids include methacrylonitrile, crotononitrile, methyl acrylate, ethyl acrylate, propyl acrylate, ethyl methacrylate, propyl crotonate, methyl crotonate, and the like. Lower aliphatic esters is taken to mean thosev esters in which the alcohol portion of the ester is an alkyl group'contai-ning from 1 to 4 carbon atoms.

While it is preferred to employ stoichiometric quanti ties of the reactants, quantities in slight excess of the theoretical may be employed. No advantage is seen in using large excesses of either reactant while some difliculties might be created in certain instances. I

The amount of water employed as catalyst may vary over a wide range from as little as 0.1% to as much as 15% by weight of the amine. Preferably, from about 3% to about 10% water provides most efiective catalysis of the reaction. 1

The. amount of cyanoethylated amine solubilizer to be employed may vary widelydepending upon the amine being reacted and the amount of water employed as a catalyst in a specific instance. }The optimum quantity is represented 'by the minimum amount which will effect a completely homogeneous solution of the reactants and the catalyst. This is readily determinable by observation or by simple testing. Usually, from about 10% .to about is maintained below the decomposition temperatures of the reaction components. .At room temperature or below, an extended period of time may be required for reaction, so it is preferred to conduct the reaction attemperatures between about 40 and 100 C. V [The aminonitriles produced'by the invention are useful as chemicalintermediates. They may be readily reduced to polyamines and the arnino group therein is available for reaction with acids, alkylene oxides, alkyl acid 'chlorides, and the likefor the preparation of many useful products such as textile assistants, solvents, etc( The aminoesterslead to detergents, emulsifying agents, curiael. The process which 'cornprises'reactiirg a tert-carbim amine-of the formula f ,B-(n-Butylamino') propionitrile I 99.

wherein R, R and R are chosen from the group consisting of alkyl, cycloalkyl, aryl, alkaryl, and aralky-l radicals containing from 1 to 12 carbon atoms with a compound selected from the group consisting of the nitriles and lower alkyl esters of acrylic acid, methacrylic acid, and crotonic acid to yield the corresponding ,B-aminonitriles and fi-aminoesters at a temperature from about 0 C. to about 200 C. in the presence of a catalytic quantity of water, said amount of Water being in the range from about 0.1% to about 15% by weight of the tert-carbinamine, and as a solubilizer therefor a watersoluble cyanoethylated amine chosen from the group consisting of secondary N-(fl-cyanoethyl) alkyl amines wherein the alkyl substituent is a lower alkyl group, secondary N-(B-cyanoethyl) cycloalkylamines and secondary N,N-bis(fl-cyanoethyl) amine, said solubilizer being present in an amount in the range from about to about 200% by weight of the carbinarnine.

2. The process which comprises reacting a tort-carbinamine of the formula wherein R, R and R" are alkyl radicals containing from 1 to 12 carbon atoms with a compound selected from the group consisting of the nitriles and lower alkyl esters of acrylic acid, methacrylic acid, and crotonic acid to yield the corresponding B-aminonitriles and fi-aminowters at a temperature from about 0 C. to about 200 C. in the presence of a catalytic quantity of water, said amount of water being in the range from about 0.1% to about by weight of the tert-carbinamine, and as a solubilizer therefor a water-soluble cyanoethylated amine chosen from the group consisting of secondary N-(fi-cyanoethyl) alkylamines wherein the alkyl substituent is a lower alkyl group, secondary N-(fl-cyanoethy-l) cycloalkylamines and secondary N,N-bis(B-cyanoethyl) amine, said solubilizer being present in an amount in the range from about 10% to about 200% by weight of the carbinamine.

3. A process for the production of aminonitriles which comprises reacting a tert-carbinamine of the formula wherein R, R and R" are alkyl radicals containing from 1 to 12 carbon atoms with acrylonitrile at a temperature in the range from about 0 C. to about 150 C. and in the presence of an amount of Water in the range from about 0.1% to about 15 by weight of the tert-carbinamine, and as a solubilizer therefor a water-soluble cyanoethylated amine chosen from the group consisting of secondary N-(p-cyanoethyl) 'alkylamines wherein the alkyl substituent is a lower alkyl group, secondary N-( 3-cyanoethyl) cycloalkylamines and secondary N,N-bis(,8-cyanoethyl) amine, said solubilizer being present in an amount 6 in the range from about 10% to about 200% by weight of the carbinamine.

4. A process for the production of 13-(tert-nonylami-no)- propionitrile which comprises reacting tert-nonylamine with acrylonitrile at a temperature in the range from about 40 C. to about C., in the presence of an amount of water in the range from about 3% to about 10% by weight of the tert-nonylamine, and as a solubilizer therefor fi-(tert-butylamino)propionitrile in an amount in the range from about 10% to about 200% by weight of said nonylamine.

5. A process for the production of B-(tert-dodecylamino) propionitrile which comprises reacting tertdodecylamine with acrylonitrile at a temperature in the range from about 40 to about 100 C. in the presence of an amount of water in the range from about 3% to about 10% by weight of the tert-dodecylamine and as a solubilizer therefor 18,,8in1inodipropionitrile in an amount in the range from about 10% to about 200% by weight of said tert-dodecyl-amine.

6. A process for the production of amino esters which comprises reacting a tert-carbinamine of the formula wherein R, R, and R" are alkylradicals containing from 1 to 12 carbon atoms with a compound chosen from the group consisting of the lower alkyl esters of acrylic acid, methacrylic acid, and crotonic acid at a temperature from about 0 C. to about 200 C. in the presence of an amount of water in the range from about 0.1% to about 15 by weight of the tert-carbinamine and as a solubilizer therefor a water-soluble cyanoethylated amine chosen from the group consisting of secondary N-(flcyanoethyl) alkylamines wherein the alkyl substituent is a lower alkyl group, secondary N-(B-cyanoethyl) cycloalkylamiues and secondary N,N-bis(;8-cyanoethyl) amine, said solubilizer being present in an amount in the range from about 10% to about 200% by weight of the carbinamme.

7. A process for the production of ethyl-fl-(tertdodecylamino) propionate which comprises reacting ethyl acrylate with tert-dodecylamine at a temperature in the range from about 40 C. to about 100 C. in the presence of an amount of Water in the range from about 3 to about 10% by weight of the tert-dodecylamine and as a solubillZCI therefor B-(cthylamino)propionitrile in an amount in the range from about 10% to about 200% by weight of said dodecylamine.

References Cited in the file of this patent UNITED STATES PATENTS 

1. THE PROCESS WHICH COMPRISES REACTING A TERT-CARBINAMINE OF THE FORMULA 